1. Field of the Invention
This invention relates to a solid oxide electrolyte fuel cell (hereinafter referred to simply as "SOFC"), and more particularly to an SOFC which is applicable to an electrolytic cell in water electrolysis and CO.sub.2 electrolysis, as well as to power generation.
2. Description of the Related Art
A typical example of a conventional plate type SOFC is shown in FIGS. 3 and 4. FIG. 3 shows a perspective view of disassembly of the conventional plate type SOFC, and FIG. 4 shows a perspective view of the assembly thereof. In the figures, the reference numeral 1 denotes a power generation film consisting of a solid oxide electrolyte film 2, an oxygen electrode 3, which is provided on the upper surface of the solid oxide electrolyte film 2, and a fuel electrode (not shown), which is provided on the under surface of the solid oxide electrolyte film 2.
An interconnector 6 is provided on the upper surface of the power generation film 1 through a corrugated air electrode side support 4 and packings 5,5, divided into two pieces to hold the air electrode side support 4 from both sides. When laminated, the air electrode side support 4 is held between the packings 5,5.
Further, the reference numeral 7 denotes an air inlet provided at the side gap of the packings 5,5. An air outlet (not shown) is provided at the other side gap of the packings 5,5, opposed to the air inlet 7.
Furthermore, on the under surface of the power generation film 1, there is provided an interconnector 10 through a fuel electrode side support 8 having a corrugated shape in perpendicular direction against the air electrode side support 4, and packings 9,9, divided into two pieces to hold the fuel electrode side support 8 from both sides. Accordingly, when laminated, the fuel electrode side support 8 is held between the packings 9,9. The reference numerals 11 and 12 denote a fuel inlet and a fuel outlet, respectively, provided at both side gaps between the packings 9,9.
The flow of fuel is in a perpendicular direction to that of air, that is, the fuel is introduced from the inlet 11 and flows into the fuel outlet 12 over both surfaces of the fuel electrode side support 8, and air is introduced from the air inlet 7 and flows into the air outlet (not shown) over both surfaces of the air electrode side support 4.
The formed cell is generally laminated to several layers to increase output. That is, to increase the output, air electrode side components such as packings 5,5 and an air electrode side support 4 are mounted on the under surface of the interconnector 10, and an oxygen electrode 3 of a power generation film 1 is provided under the air electrode side components. Furthermore fuel electrode side components such as packings 9,9 and a fuel electrode side support 8 are mounted on the upper surface of interconnector 6, and a fuel electrode of power generation film 1 is provided above the fuel electrode side components. In this manner, the lamination succeeds to increase the output.
As described above, a conventional SOFC needs to be provided with supports 4, 8, and packings 5,5 and 9,9 at the air electrode side and fuel electrode side, respectively, in addition to the power generation film 1 and interconnectors 6,10. The configuration increases the number of components, which increases the work steps to fabricate components and which takes time for assembling a cell. To solve the problems, an invention which eliminated the supports 4,8, was disclosed in Japanese Patent Application Hei 5-6048 of "Solid Oxide Electrolyte Fuel Cell", filed by the applicant of the present invention. The above invention is characterized by an electrical joint of a power generation film having a dimpled pattern with an interconnector.
The device disclosed in the above-identified Japanese application has, however, the following problems:
(1) Packings which hold a power generation film having a dimpled pattern are necessary to be disposed between interconnectors as illustrated in FIGS. 3 and 4. If the packings are made from a rigid material, extreme accuracy in the height of the individual dimples on the power generation film is required. However, such an accuracy is extremely difficult to obtain in the present processing technology for the power generation film. If the packings are fabricated from a soft material, various problems arise caused by the gas permeability of the packing material itself. PA1 (2) Further, in the type shown in FIGS. 3 and 4, which introduces and discharges air and fuel from both sides of the cell, the air inlet 7 and outlet need be added, compared with the type illustrated in FIG. 5 where the air is introduced and discharged from the top and bottom of the cell. In addition, a solid oxide electrolyte film is required to reduce its thickness to increase the ion conductivity. A thin structure may induce a problem of strength at the openings of the air inlet and outlet. As a result, the openings need to be reinforced using a support such as a round tube. The countermeasures increase the number of components and increase the time for fabricating and assembling them. PA1 (3) A conventional configuration requires the power generation film to have a flat shape at the region sandwiched by packings even though the power generation film is dimpled as a whole. The requirement makes the fabrication of power generation film further difficult because the power generation film contracts to approximately 70% during the firing process compared with that before firing to have a specified cell.
The object of the invention is to solve the problems described above and to provide a solid oxide electrolyte fuel cell which does not need special packing and which simplifies the manufacturing process thereof. Moreover, even when air and fuel are introduced and discharged from the sides of the cell, the openings as the inlet and outlet should not need special support.